Power plant



B. BROIDO POWER PLANT May 27, 1 930.

Filed NOV. 24, 1926 2 Sheets-Sheet 1 A TTORNE Y.

.BEI/VJAM/A/ .BPO/DO. I N V EN B. B ROIDQ POWER PLANT May 27, 1930.

Filed Nov. 24, 1926 2 Sheets-Sheet 2 fiEA/QAM/A/ zEO/ o. INVENTOR.

A TTORNE Y.

Patented May 27, 1930 UNITED STATES PATENT OFFICE BENJAMIN BROIDO, onNEW YORK, N. Y., ASSIGNOR '20 THE SUPERHEATER COMPANY,

on NEW YORK,. N. Y.

POWER PLAN T Application filed November 24, 1926. Serial No. 150,478.

My invention relates to power plants and has for its general object theimprovement in the efliciency and operating economy thereof..

.In commercial power plants where steam is utilized in compound primemovers, it is a common practice to reheat the exhaust steam leaving thehigh pressure stage before it is utilized in the low pressure stage.Various methods have been proposed for reheating this exhaust steam, themost common means being either by returning the steam from a pointbetween stages to reheaters located in the boilers or by reheating theexhaust steam by means of live steam.

\Vith the present methods of reheating by means of live steam, the lowpressureexhaust steam cannot be brought to a temperature materiallyhigher than that of the saturation temperature of the live steam used asa heating "medium, even though the latter be superheated. and in orderto overcome this difiiculty it has been suggested that the exhaust steammight be reheated by steam at a very high pressure generated in aspecial Boiler.

' Reheating of the exhaust steam is usually considered only inconnection with large turbines, and the amount of steam required forreheating in such cases is considerable. The amount of heating steamrequired to raise the temperature of a given quantity of low pressureexhaust steam 100 deg. is usually from 5 to 6 per cent of the amount ofsteam heated,

' and, if as is desirable, the reheated steam is raised 300 deg. intemperature, over 15 per cent of the total amount of steam reheated isrequired for reheating. In the case of a large unitof 50,000 kilowattsor more, this would involve a comparatively large high pressure boilerto supply steam for reheating purposes and the cost of such aninstallation, in addition to the complication involved. would ordinarilymake this arrangement, al-

though desirable from the standpoint of efficiency, economicallyimpractical.

In accordance with my invention, the advantages of reheating by the useof live steam, that is to say. the elimination of the complicationsnecessary for reheating in the boilers, are retained and the reheatingof the exhaust steam is accomplished by the use of a comparatively smallhigh pressure boiler which supplies heating steam only for the finalstage of the reheating.

In the accompanying drawings I have shown in diagrammatic formillustrative embodiments of my invention, Fig. 1 representing apreferred form of construction, Fig. 2 representing a modification, andFig. 3 being a cross section of a portion of Fig. 2 taken at rightangles thereto.

Referring now to the form shown in Fig. l, the numeral 10 represents aconventional form of boiler which may be one of a battery comprising themain source of operating steam for the plant. The boiler is providedwith the usual superheater 11 from which steam is delivered through theconduit 12 to the high pressure unit 13 of theplant, which in thepresent instance has been illustrated as a turbine. The high pressureunit exhausts through the conduit 1-1 into a reheater 15 and passes fromthe latter through the conduit- 16 to the low pressure unit 17 which hasbeen shown as a second turbine exhausting into the condenser 18. 'hile Ihave shown the power plant as comprising two separate turbines. itisapparent that the plant may consist of a multiple cylinder turbine oreven a compound reciprocating unit. heating elements 19 and :20 which Ihave illustrated diagrammatically as tubular coils but which may be ofany desired form. Theheating element 19 is supplied with live steam fromthe main boiler 10 through conduit 21 and the steam supplied thereto ispreferably entirely condensed in the coil, the

The reheater 15 is provided with two condensate passing'throua'h the.conduit 22 to the hot-well 23. It is to be noted in this connection thatthe heating element 19 is placed at the end of the reheater where theexhaust steam enters.

The heating element 20, placed adjacent the outlet end of the reheater,is supplied through conduit 24 with live steam from a boiler 25 whichgenerates steam at a pressure materially higher than the pressureexisting in the main boiler '10.

The steam supplied through the conduit 24 is preferably entirelycondensed within the heating element 20 and the condensate therefrom isreturned directly to the boiler 25.

Because of the fact that the load on the boiler 25 is comparativelyconstant in character, this boiler may advantageously be of thecontinuous coil or flash type, to which the condensate from the heatingelement 20 is returned directly through the conduit 26.

In operation, the live steam supplied to the heating element 19 from themain boiler will serve to initially heat the exhaust steam to atemperature substantially that of the saturation temperature of the mainsteam supply. This temperature may be slightly exceeded because of thesuperheat in the steam con- .densed in the element 19, but in ordinarypractice the saturation temperature will not be materially exceeded andfor this reason it is not essential that the steam supplied to thefilyater from the main boiler be superheated.

order to simplify piping arrangements, superheated steam may be suppliedto the element 19, but saturated steam will serve equally well, as themajor portion of the heating is accomplished by the latent heat ofvaporization released by the condensation of the steam in the element19.

After the exhaust steam has been initially heated by contact with theelement 19, its temperature is further raised by contact with theelement 20 which is supplied with steam generated at a pressure suchthat the saturation temperature is considerably above the temperature towhich the exhaust steam has been. raised by the element 19. As the steamfrom the high pressure boiler 25 is preferably utilized wholly forheating purposes, it is not necessary to superheat this steam, as theadvantage to be derived from superheating is not sufficient to warrantthe expense of superheating equipment, and I therefore prefer touse-saturated steam in this element. It will be obvious, however, that,if desired, the steam generated in the high pressure boiler could besuperheated before being utilized in the reheater.

Because of the comparatively small ran e through which the exhaust steammust Ee heated by the element 20, it is evident that the amount of steamrequired from the boiler 25 will be comparatively small. and the cost ofthis boiler may in consequence be materially reduced. The cost of thehigh pressure boiler is further reduced by the fact that a simple flashboiler may be utilized for the purpose, and b condensing all of thesteam generated in t e reheater and returning it directly to the boilerthe necessity of a boiler feed pump may be eliminated, as the necessarycirculation may be obtained by thermal action.

In Figs. 2 and 3 I have shown a modified arrangement in which both themain boiler 10 and the auxiliary high pressure boiler 25 are installedin a common setting. In other respects, the arrangementof the severalunits in the plant is the same as that previously described, but in thisarrangement I prefer to use an auxiliary high pressure boiler of thecirculating type. For purposes of illustration I have shown the mainboiler 10 as a conventional horizontal cross-drum type with theauxiliary boiler located at the top of the first and second passes ofthe main boiler. The auxiliary boiler is shown as of the same generaltype as the main boiler, with the steam generating tubes 27 locatedtransversely of the main boiler tubes and delivering through suitablecirculators to the steam drum 28 from which steam is led through theconduit 24' to the heating element 20. The condensate from the element20 is returned through the conduit 26 to the water space of the boiler25', and it will be evident that in this form of construction no pumpwill be required to .efi'ectcirculation through this system which forms,as does the one previ-' ously described, a closedcircuit all portions ofwhich are under substantially the same pressure.

Obviously, the specific form of high pressure boiler incorporated in thesetting of the main boiler is not an essential element of the invention,but I prefer to utilize a boiler of the circulating type in this form ofconstruction because of the fact that fluctuations in the load on themain boiler will produce variations in the amount of heat suppliedthereto which would adversely affect the operation of a flash typeboiler.

While I have described my invention in connection with certain preferredembodiments thereof, it will be obvious that many changes in thearrangements and details of construction may be made b those skilled inthe art., and my invention 1s. therefore, not to beconsidered as limitedby the illustrative examples which I have chosen, but is to beconsidered as embracing all such changes and modifications as may fallwithin the scope of the appendedclaims. 4

I claim:

1. In'a steam power plant, the method of reheating steam exhausted fromone consumer to a secondconsumer which consists in initially heatingsaid steam with steam from the main steam supply and finally heatingsaid steam with steam at a pressure higher than that of the main steamsupply.

2. In a power plant, the method of heating steam exhausted from oneconsumer to a second consumer which consists in initially heat ing saidsteam with superheated live steam from the main steam supply and finallyheating said steam with saturated steam at a pressure higher than thatof said superheated steam supply.

The method of generating power which consists in generating steamsupplies at different pressures, superheating the steam generated at thelower pressure, utilizing a portion of the superheated steam inaconsumer, initially heating the exhaust steam from said consumer with aportion of the superheated steam, finally heating the exhaust steamfurther with the steam generated at the higher pressure, and utilizingsaid finally heated exhaust steam in a low pressure consumer.

a. lln a power plant, a main steam supply, a high pressure consumer, alow pressure consumer operating on exhaust steam from said high pressureconsumer, means for initially reheating the exhaust steam from said highpressure consumer with live steam from the. mam supply, and means forfinally reheating said exhaust steam with steam at a pressure above thatof the main steam supply.

5. ln a power plant, a high pressure cousumer, a low pressure consumer,a connection supplying exhaust steam from the high pressure consumer tothe low pressure consumer, a reheater in said connection, a main steamgenerator supplying operating steam to said high pressure consumer andheating steam to said reheater, and an auxiliary steam generatorsupplying additional heating steam to said reheater. I

6. In a power plant, a high pressure consumer, a low pressure consumer,a connection supplying exhaust steam from the high pressure consumer tothe low pressure consumer, a reheater in said connection, a main'steamgenerator supplying operating steam to said high pressure consumer andheating steam to said reheater, and an auxiliary steam generatorsupplying additional heating steam to said reheater at a pressure abovethat generated in said main generator.

7. In a power plant, a high pressure consumer, a low pressure consumer,a connection supplying exhaust steam from the high pressure consumer tothe low pressure consumer, a reheater in said connection, a mainsuperheated steam generator supplying superheated operating steam tosaid high pressure consumer and superheated live steam to said reheater,and an auxiliary steam generator supplying saturated steam to saidreheater at a pressure higher than that of the superheated steam.

8. In a power plant, a main boiler, a superheater therein, a highpressure turbine, a low pressure turbine, a conduit supplying exhauststeam from the high pressure turbine to the low pressure turbine, areheater in said conduit comprising a heating element adjacent the inletend. of the reheater and a heating element adjacent the outlet end ofthe reheater, a conduit connecting said superheater with saidfirst-named element, an auxiliary boiler operating at a pressure abovethat of the main boiler, and a conduit connecting said auxiliary boilerwith said last-named element.

9. In a power plant, a main steam supply, an exhaust steam reheatercomprising a heating element adjacent the inlet end of the re heater anda heating element adjacent the outlet end of the reheater, a conduitleading from the main steam supply to said firstnamed element, and aclosed circuit system supplying steam to said last-named element at apressure above that of the main steam supply.

10. In a power plant, a main steam supply, an exhaust steam reheatercomprising a plurality of heating elements, a conduit leading from themain steam supply to one of said elements, and a closed circuit systemsupplying steam to another of said elements at a pressure above that ofthe main steam supply, said system comprising a continuous flow boiler,a conduit leading from the outlet end of said boiler to said element,and a conduit leading from said element to the inlet end of said boiler.

11. In a power plant, a high pressure consumer, a low pressure consumer,a connection supplying exhaust. steam from the high pressure consumer tothe low pressure consumer, a reheater in said connection, a main steamgenerator supplying operating steam to said high pressure consumer andheating steam to said reheater, and a separately fired auxiliary steamgenerator supplying additional heating steam to said reheater at apressure above that generated in said main generator.

12. The method of generating power which consists in generating steamsupplies at different pressures, utilizing steam generated at a pressurebelow the highest pressure in a consumer, initially heating the exhauststeam from said consumer with other steam gener ated at a pressure belowthe highest pressure, finally heating the exhaust steam further withsteam generated at a higher pressure, and utilizing said finally heatedexhaust Steam in a low pressure consumer.

13. The method of generating power which consists in generating steamsupplies at different pressures, utilizing steam generated at a pressurebelow the highest pressure in a consumer. initially heating the exhauststeam from said consumer with other steam at substantially the samepressure as that of the steam supplied to the consumer, finally heatingthe exhaust steam further with steam generated at the highest pressure,and utilizing said finally heated exhaust steam in a low pressureconsumer.

14. The method of generating power which consists in generating steam attwo diflerent pressures, utilizing steam generated at the lower pressurein a consumer, initially heating the exhaust steam from said consumerwith steam generated at the lower pressure, finally heating the exhauststeam further with steam generated at the higher pressure, and utilizingsaid finally heated exhaust steam in a low pressure consumer.

BENJAMIN BROIDO.

